Incoming and resident animals at NIEHS are monitored for morphological abnormalities, spontaneous diseases and parasitism. The health status of research animals is vital to reliable interpretation of experimental data. Sporadic respiratory disease among laboratory rodents is associated with Sendai virus, usually in association with Pasteurella pneumotropica. Enteric pathogens have not been detected. Pinworm infections are infrequent. No pathologic lesions can be attributed to these nematodes. Pasteurellosis in NZW rabbits has not been encountered since purchasing them from a new source. Infectious disease in guinea pigs or hamsters has not been encountered.